diff --git a/README.md b/README.md
index e5a9643b..3ff57673 100644
--- a/README.md
+++ b/README.md
@@ -28,7 +28,24 @@
 curl -fsSL https://raw.githubusercontent.com/Ark0N/Codeman/master/install.sh | bash
 ```
 
-This installs Node.js and tmux if missing, clones Codeman to `~/.codeman/app`, and builds it. You'll need at least one AI coding CLI installed — [Claude Code](https://docs.anthropic.com/en/docs/claude-code) or [OpenCode](https://opencode.ai) (or both). After install:
+This installs Node.js and tmux if missing, clones Codeman to `~/.codeman/app`, and builds it.
+
+**Install from a fork or specific branch:**
+```bash
+curl -fsSL https://raw.githubusercontent.com/douchekr/Codeman/feat/input-cjk-form/install.sh | \
+  CODEMAN_REPO_URL=https://github.com/douchekr/Codeman.git \
+  CODEMAN_BRANCH=feat/input-cjk-form bash
+```
+
+The installer supports these environment variables:
+
+| Variable | Default | Description |
+|----------|---------|-------------|
+| `CODEMAN_REPO_URL` | upstream Codeman | Custom git repository URL |
+| `CODEMAN_BRANCH` | `master` | Git branch to install |
+| `CODEMAN_INSTALL_DIR` | `~/.codeman/app` | Custom install directory |
+| `CODEMAN_SKIP_SYSTEMD` | `0` | Skip systemd service setup prompt |
+| `CODEMAN_NONINTERACTIVE` | `0` | Skip all prompts (for CI/automation) | You'll need at least one AI coding CLI installed — [Claude Code](https://docs.anthropic.com/en/docs/claude-code) or [OpenCode](https://opencode.ai) (or both). After install:
 
 ```bash
 codeman web
diff --git a/install.sh b/install.sh
index eefdd199..c5cf2433 100755
--- a/install.sh
+++ b/install.sh
@@ -9,6 +9,8 @@
 #   CODEMAN_INSTALL_DIR       - Custom install directory (default: ~/.codeman/app)
 #   CODEMAN_SKIP_SYSTEMD=1    - Skip systemd service setup prompt
 #   CODEMAN_NODE_VERSION      - Node.js major version to install (default: 22)
+#   CODEMAN_REPO_URL          - Custom git repository URL (default: upstream Codeman)
+#   CODEMAN_BRANCH            - Git branch to install (default: master)
 
 set -euo pipefail
 
@@ -17,7 +19,8 @@ set -euo pipefail
 # ============================================================================
 
 INSTALL_DIR="${CODEMAN_INSTALL_DIR:-$HOME/.codeman/app}"
-REPO_URL="https://github.com/Ark0N/Codeman.git"
+REPO_URL="${CODEMAN_REPO_URL:-https://github.com/Ark0N/Codeman.git}"
+BRANCH="${CODEMAN_BRANCH:-master}"
 MIN_NODE_VERSION=18
 TARGET_NODE_VERSION="${CODEMAN_NODE_VERSION:-22}"
 NONINTERACTIVE="${CODEMAN_NONINTERACTIVE:-0}"
@@ -1081,7 +1084,7 @@ main() {
         mkdir -p "$(dirname "$INSTALL_DIR")"
 
         # Clone repository (shallow for speed)
-        git clone --quiet --depth 1 "$REPO_URL" "$INSTALL_DIR"
+        git clone --quiet --depth 1 --branch "$BRANCH" "$REPO_URL" "$INSTALL_DIR"
         cd "$INSTALL_DIR"
     fi